Indeed, in current microwave equipment, parasitic signals of frequency generally lying between 10 Hz and 10 MHz are systematically generated by the primary bus of DC voltage converters and are found on the supply voltages of microwave circuits. These parasitic signals, of low frequency relative to the usual microwave frequencies, which are of the order of one to several tens of GHz, are difficult to filter and are transmitted on output from the microwave units.
The parasitic signals are thus carried by the microwave signals and may cause disturbances.
The conducted susceptibility makes it possible to measure the reaction of units in relation to parasitic signals. The attenuation of the parasitic signals will thus be measured, in dBc. The higher the conducted susceptibility, the more significant the attenuation of the parasitic signals and therefore the better the information transmission on the microwave circuit. The conducted susceptibility is therefore generally the subject of specification required when designing microwave equipment. This required conducted susceptibility is generally dependent on the frequencies of the parasitic signals: the higher the frequency, the higher the conducted susceptibility must be. For example, for parasitic signals at 10 MHz, a susceptibility of −55 dBc may be demanded. The closer the conducted susceptibility is to zero, the higher the power exhibited by the parasitic signals.
Currently, the attenuation of parasitic signals is done by adding complementary units, mainly at the level of the DC/DC converter, DC voltage converter, present on all microwave equipment. Indeed, the parasitic signals are essentially generated by the DC supply or by the DC/DC converter on account of its chopping frequencies. Polarization networks may make it possible to attenuate these parasitic signals.
Today, one of the favored avenues for improving microwave equipment aboard satellites resides in reducing the volume of DC/DC converters and making them lighter. One of the solutions is therefore to dispense with certain elements allowing the attenuation of parasitic signals.
However, there does not exist in the state of the art any means of substitution making it possible not to undergo the presence of parasitic signals at the microwave circuit level: this is the subject of the present patent application. The invention consists indeed of a microwave electronic device carrying out the attenuation of the parasitic modulated signals present at the input of said device, said parasitic modulated signals being transmitted to the microwave circuit by the DC/DC converter, and their frequency band being known since it is related to the chopping frequency of said DC/DC converter. The invention makes it possible to do away with the presence of units dedicated to the attenuation of the parasitic signals at the level of the DC/DC converter or of the power supply of the complete item of equipment. With the DC/DC converter representing today about 45% to 50% of the volume of the microwave equipment aboard satellites while the whole of the microwave chain represents about 20% thereof, the expected gain as regards volume is very significant.